Competitive athletes are constantly in search of tools to fine-tune each aspect of their game. For competitive golf players, the key to improvement often entails selection of equipment that optimally fits their specific swing characteristics, Thus, a competitive golf player benefits from using tools that enable them to observe and analyze alternative equipment as well as each aspect of their swing. By doing so, a player can make changes necessary for achieving optimal performance, which may ultimately lead to a better score.
The tools that are often used to aid competitive golf players are commonly referred to as launch monitors. A launch monitor typically includes an imaging system that is capable of imaging dynamic events such as the motion of the golfers club, golf balls, or the body of the golfer. The image may include one or more image frames. The image or images may then be analyzed using a desired mathematical algorithm that enables the kinematic characteristics of the club, ball, or body to be determined.
Over the past thirty years, launch monitors have been developed and improved upon. An example of one of the earliest high speed imaging systems, entitled “Golf Club Impact and Golf Ball Monitoring System,” to Sullivan et al., was filed in 1977. This automatic imaging system employed six cameras to capture pre-impact conditions of the club and post impact launch conditions of a golf ball using retroreflective markers. Shortly thereafter, a two-camera system capable of triangulating the location of retroreflective markers appended to a club or golf ball in motion was developed. Such systems are disclosed in U.S. Pat. Nos. 5,471,383 and 5,501,463.
Additional kinematic measurement systems have been developed over the years implementing and building on this concept. For example, U.S. Pat. No. 5,906,547 measures the speed and trajectory of a specialized golf club through the use of specific club-identifying markers, and extrapolates those measurements to determine the kinematics of an imaginary golf ball. U.S. Pat. Nos. 7,292,711 and 7,324,663 use a single camera to determine the velocity, launch angle, and spin of the ball after being struck by a club. Other systems have been developed that are configured to the kinematics of both the golf ball and golf club. For example, U.S. Patent Publication No. 2002/0155896 describes a method of monitoring both golf clubs and balls in a single system. U.S. Patent Publication No. 2002/0173367 generally discloses the use of fluorescent markers in the measurement of golf equipment.
Other systems have been introduced based upon the same principles discussed above for measuring the kinematics of golf clubs and balls. For example, U.S. Pat. No. 8,622,845 generally discloses a portable launch monitor that uses multiple cameras and computational means to generate and display launch angle and other various related measurements. In addition, U.S. Pat. No. 9,516,276 discloses a system that utilizes the camera on an individual's mobile device to measure the speed and trajectory of a struck soccer ball.
Despite the general advancements discussed above, the known systems have drawbacks. For example, several of the systems above do not have the capacity to provide accurate measurements and instead rely on extrapolation and assumptions to determine the kinematics of the clubs and balls. In fact, U.S. Pat. Nos. 7,292,711, 7,324,663, and 9,516,276 make assumptions on the size of the tracked ball and then extrapolate measurements based upon the assumptions and captured data. Extrapolated measurements based upon the assumptions typically lead to inaccuracies. In addition, many prior art systems capture only a single image of the golf objects that is double exposed, which can result in a ghost-like double image of the moving object. Furthermore, in such instances, light sources that can provide a flash for the double exposure (e.g., strobes) are needed, which adds to the overall components required by the system, Additionally, with more strobe firings, the objects appear fainter, which then makes it difficult to distinguish the objects from the background.
One way to address this issue is through the use of color. In fact, many known systems employ a combination of strobes, black and white cameras with color filters, and fluorescent markers on the moving objects (i.e., the golf ball and/or golf club). The light emitted through the strobe is filtered by the color filters on the cameras, making the fluorescent markings on the object the only items visible to the camera. However, this purported solution does not fully address the issue because normal white light contains all colors. Furthermore, under some lighting conditions, in which external light (e.g., sunshine) is shining directly on the object, both the extra light and the intended light (e.g., strobe or laser reflected off of markers on the ball or the ball itself) can be detected by the cameras. An object in bright sunlight that is white, shiny metal, or a combination thereof that is in the field of view of the camera may have enough intensity in the same range as the color filter to show through. Because balls are usually bright white, this is problematic when trying to determine the kinematics of a golf club where the ball is part of the background. Likewise, because golf clubs are typically formed from metal, determining the kinematics of the ball with the golf club in the background is also problematic when using such systems. The detection of two different sources of light off of the target results in the misidentification of markers, causing computations (e.g., algorithms) to function improperly, which typically results in missing swing and/or shot data and may result in a partially or completely non-functional system.
In addition, the use of only black and white images limits the monitoring to only specific colors of balls. For example, only white balls or colored balls that do not fluoresce in the orange and green band of the light spectrum can be used with such launch monitor systems.
Therefore, there is a need in the art for a system that addresses and overcomes the shortcomings discussed above.